Preparation of PDMS/PVDF Composite Pervaporation Membrane Modified with Hydrophobic TiO2 Nanoparticles for Separating Formaldehyde Solution

Abstract

In this paper, polydimethylsiloxane (PDMS) was blended with hydrophobic TiO2 nanoparticles and then coated on top of the polyvinylidene fluoride (PVDF) ultrafiltration membrane to form the (PDMS/TiO2)/PVDF composite membrane. The structure, morphology and physical property of the composite membrane were characterized by FTIR, SEM, contact angle measurement, and dry-wet swelling degree test. The TiO2 was uniformly distributed in the PDMS matrix, and the composite membrane showed higher affinity to formaldehyde than water. The membrane was used to separate the 1000 ppm formaldehyde water solution through a pervaporation (PV) process. The results showed that the membrane could selectively permeate formaldehyde over water and the best separation performance could be achieved at 50°C with a separation factor of 11.25, and a total flux of 187.72 g·m-2·h-1, which were better than the pristine PDMS/PVDF membrane with separation factor of 10.66 and total flux of 115.52 g·m-2·h-1. Hence, adding TiO2 not only increased the membrane flux, but also increased the separation factor of the composite membrane. This study showed that pervaporation technology had the potential for treating formaldehyde wastewater.